1. Field of the Invention
The present invention relates to a core bar for a rubber crawler and a rubber crawler used for a farm machine, a construction machine and the like and, to be more specific, to an outside rail type rubber crawler.
2. Description of the Related Art
In Japanese Examined Utility Model Publication No. HEI 7-17658, there is proposed a core bar for a rubber crawler having a pair of angular protruding parts (protrusions for preventing the coming-off of a rolling wheel) formed on both sides of an engaging part at the center between right and left wing parts, on outer side of each of the angular parts described above is formed a shoulder part (outside rail) elevated with respect to the wing parts of the core bar, wherein the respective shoulder parts are formed with overhanging parts that overhang in the front-rear direction (in the widthwise direction of the wing part), and wherein the top surfaces of the respective shoulder parts are slanted upward from the center to the end portions of the front and rear overhanging parts; and a crawler in which the core bars for a rubber crawler are embedded in a rubber crawler body with the top surfaces (rail surfaces) of the shoulder parts described above exposed on the inner circumferential surface of the rubber crawler so that the top surfaces of the shoulder parts form a rolling wheel track against which the outside collars of an outside collar type rolling wheel are abutted.
According to the related art described above, when the overhanging part is sunk, it is brought closer to an adjacent shoulder part (outside rail) in the circumferential direction (in the lengthwise direction) of the crawler to narrow the distance between the core bars, so that the rolling wheel track is made nearly continuous in the circumferential direction, thereby reducing vibrations as much as possible.
However, since the sinking of the overhanging part increases the height difference between the adjacent overhanging parts in the circumferential direction of the crawler and, when the rolling wheel is transferred to the next overhanging part, the rolling wheel collides with the next overhanging part causing noises and vibrations.
In particular, in a truck loader, a vibration roller, a bulldozer or the like, which mostly runs at comparatively high speeds, the collision of the rolling wheel with the overhanging parts tends to cause large noises and damages the overhanging part or the rolling wheel.
The present invention has been made to solve these kinds of problems in the related art. It is, therefore, an object of the present invention to provide a core bar for an outside rail type rubber crawler that is capable of reducing height differences between the adjacent overhanging parts and collisions between the rolling wheel and the overhanging part which are caused by sinking of the overhanging part due to a transfer of the rolling wheel from one overhanging part to the next one, and a rubber crawler in which such core bars are embedded.
The present invention provides an outside rail type core bar capable of substantially reducing collision noises caused by a rolling wheel and suppressing damage accompanied by the collision, and an outside rail type rubber crawler using such core bars, and thus, is advantageous in that it solves the problems described above in the related art.
A core bar for a rubber crawler in accordance with the present invention includes an engaging part which connects a right wing part with a left wing part, right and left protrusions formed on the right and left sides of the engaging part in the lengthwise direction of the core bar for guiding a rolling wheel, and right and left outside rails formed on the outer sides of the right and left protrusions with respect to a center of the core bar in the lengthwise direction thereof and formed with overhanging parts overhanging in the widthwise direction of the wing part.
The core bar for a rubber crawler of the present invention is characterized in that each of the overhanging parts has a front or rear edge portion on the top surface, the top surface being formed with a surface that slants downward from a rail surface of the outside rail.
When the rolling wheel is transferred to the rail surface of the next outside rail, this constitution makes it possible for the rolling wheel to be transferred on a nearly horizontal flat surface, even if the overhanging part has sunk, thereby avoiding the rolling wheel from colliding with the overhanging part, and thus, ensuring a smooth transfer.
In a preferable embodiment, it is recommended that each of the right and left outside rails has an overhanging part extending only on one of the front and the rear sides thereof in the widthwise direction of the wing part and that the overhanging parts of the right and left outside rails are arranged to extend on the opposite sides to each other.
Further, it is recommended that each of the right and left outside rails have overhanging parts on both the front and the rear sides in the widthwise direction of the wing part and that the overhanging parts of the right and left outside rails are equal or different in length to or from each other, so that the right and left outside rails are equal or different in length to or from each other.
Still further, it is recommended that each of the rail surfaces of the right and left outside rails is formed, in the lengthwise direction of the rail, in a horizontally extending flat surface, in a flat surface slanting upward from one end of the rail to the other end thereof including the overhanging part, or in a concavely curved surface slanting upward from a center toward opposite ends of the rail.
Still further, a rubber crawler in accordance with the present invention, in which the above-mentioned core bars for a rubber crawler are embedded, is characterized in that the core bars for a rubber crawler are embedded in a rubber crawler body with the rail surfaces of the right and left outside rails exposed on the inner circumferential surface of the rubber crawler body so that the rail surfaces of the right and left outside rails form a rolling wheel track against which the outside collars of the rolling wheel are abutted.
Still further, it is recommended that the core bars for a rubber crawler are embedded in a rubber crawler body with the rail surfaces of the right and left outside rails exposed in a staggered arrangement on the inner circumferential surface of the rubber crawler body so that the rail surfaces of the right and left outside rails form a rolling wheel track against which the outside collars of the rolling wheel are abutted.
Still further, it is recommended that the rubber crawler body has rubber protrusions raised from the rail surface between the right and left outside rails adjacent to each other in the circumferential direction (in the lengthwise direction) of the crawler.
With this arrangement, when the rolling wheel is transferred from one rail surface to the next one, the rubber protrusions are elastically deflected to ensure a smooth transfer of the rolling wheel.
These and other objects and advantages of the present invention will be made clear by the following description of the preferred embodiments when consider together with the accompanying drawings.